Analysis of Genetic Architecture for Ten Genotypes of Bread Wheat Using Half Diallel Crosses Under Nitrogen Stress

Abstract

This study included 10 genotypes of bread wheat are M45, Yakora, Giza168, Sids 12, SK95, Misr2, Giemiza 9, Sahel 1, Sids14, and Silano. The genotypes (parents and F1 crosses) were cultivated at the research station of the Department of Field Crops of the College of Agriculture at the University of Kirkuk, during the season (2021-2022) in two separate experiments on sufficiency and insufficiency of the nitrogen element using a Randomized Complete Block Design (R.C.B.D) and with three replications, to estimate the general and specific combining ability, gene action and some genetic parameters. The results of the statistical and genetic analysis showed that there are highly significant differences for the general and specific combining ability values and that the ratio of the combining ability variance components to the specific combining ability variance components was less than the one for nitrogen sufficiency and insufficiency for all the studied traits. Sids14 variety excelled in its desirable effects of general combining ability, followed by Sr. (Sids12). The hybrid (M45 × Sids14) had the highest desired values for the effects of the special combining ability at nitrogen levels for all the traits studied, followed by the cross (Sahel 1 × Sids 12) also for all the traits studied except for The number of spikes plant-1 when there was insufficient nitrogen. The heritability broad sense was high with sufficient and insufficient nitrogen, while heritability narrow sense was high with sufficient nitrogen in the number of grains spike-1 and grains yield plant-1 (gm) and medium in The number of spikes plant-1 and the weight 1000 grains (gm) and the biological yield in the insufficient amount of the nitrogen element, the heritability narrow sense was medium in all studied traits. The average degree of dominance was greater than one when nitrogen was sufficient and insufficient, which indicates the existence of Over dominance, and the expected genetic advance as a percentage was low except for the number of grains spike-1 when nitrogen was sufficient and the grains yield plant-1 (gm) when nitrogen was insufficient, as it was medium. (11.908 and 12.250), respectively, these parents that are superior in the general combining ability with high phenotypic significance can be included in wheat breeding programs to produce hybrids that are superior in the specific combining ability that can be invested in the following generations with in the breeding programs to reach the best promising varieties with future nitrogen insufficiency.